How an MRI Works

Getting an MRI can be a stressful experience. You have to remain completely still so that your physician can get an image of the inside of your body. You may be wondering, as you lay there, how this machine works. We hope to demystify them here, with a quick guide to how MRIs function.

Magnets

The main component of an MRI is the magnet – and we aren’t talking about a refrigerator magnet. The magnet is capable of producing a powerful, stable magnetic field around the patient. The magnetic field is created by coils of wire, through which a strong electric current passes.

Radiofrequency Waves

An MRI machine also contains coils that correspond to different areas of the body. The coils conform to the shape of the body during the exam. These coils are used to transmit radio frequencies into the patient’s body.

The Process

The MRI machine uses these radio waves to create an RF pulse (Radiofrequency Pulse) which respond to hydrogen atoms in the body. The pulse is applied to the specific area of the body that is being scanned. While this is happening, another set of magnets alter the magnetic fields to pinpoint the area that needs to be scanned – this process is the reason MRI machines make so much noise.

Interpreting the Image

When the RF pulse shuts off, the hydrogen atoms that were affected return to their normal positions. These atoms send a signal that is picked up by the coils and sent to the computer, which then converts the signal to an image.